If you can remove the collection plumbing at the bottom of the cooler, or at least protect it, a 10 gallon round can serve double duty as a swamp cooler for the fementation carboy. My 6 gallon PET BetterBottle fits nicely in the round cooler; add ice at the top and drain excess water from the bottom.

Has anybody noticed if a round versus rectangular cooler has more stuck sparges?

I have both, and pretty much abandoned the round cooler due to slower or stuck sparges. Not that it happened often, but the round just seems more prone to it. The grain bed is a lot deeper with a round cooler, so there's a greater risk of compaction. If you go with round, just start your vorlauf and runoff slow to set the grain bed well, then open it up a bit more. When I use the round cooler, I rarely open the valve more than halfway. With the rectangular cooler, I let 'er rip full blast.